1. Field of the Invention.
The invention relates to blood exchange transfusions in humans. And more particularly, to device for exchange transfusions in newly born babies or children.
2. Description of the Prior Art.
The conventional method of performing exchange transfusions in newly born babies is as follows: A doctor sits close to the baby and manipulates a syringe which is connected to a three-way stop cock, the three stop cock connections being (1) the baby's umbilical arterial or venous line, (2) a source of fresh blood, and (3) a container for the waste blood. The doctor first sets the stop cock to the umbilical arterial or venous line and withdraws ten to twenty cc of blood from the baby into the syringe; the stop cock is then adjusted to the waste container line and the blood in the syringe is forced into the waste container. Next the stop cock is adjusted to the fresh blood source line and the syringe is filled with ten to twenty cc of fresh blood; and then the stop cock is adjusted to the umbilical arterial or venous line and the fresh blood forced into the baby. The cycle of withdrawal, discard, reload, and injection may be repeated as necessary. This conventional method has led to many reported complications, including the following: (1) the withdrawal of ten to twenty cc of blood from a baby results in a hypovolemic condition, which may severely effect the circulation and perfusion of the vital organs; (2) the injection of ten to twenty cc of blood into the baby may result in a hypervolemic condition; (3) by withdrawal and injection at different times, the blood pressure of the baby may go up and down following each cycle, and sudden changes in blood pressure is dangerous and could aggrevate the risk of developing intracranial bleeding, especially in very premature babies; (4) withdrawal of blood from the umbilical arterial line is in accord with the physiologic flow, however the injection of fresh blood into the umbilical arterial line is contra to the physiologic flow and may disturb the circulation, giving rise to harmful effects; (5) the withdrawal and injection of blood puts the baby under severe stress, especially for the heart and may be the cause of cardiac arrest; and (6) even if an umbilical venous line is used in lieu of the umbilical arterial line, sudden change of blood pressure could interfere with the portal circulation and lead to development of necrotizing enterocolitis.
The prior art also contains devices for a continuous pumping of blood from a human through a dialyzer and back into the human. U.S. Pat. No. 2,689,565 to Gobel discloses such a device employing two syringes in a parallel push-pull arrangement so as to maintain an approximately constant blood flow by means of one-way valves.
The prior art also contains a device employing two microinfusion roller pumps, one pump for withdrawing blood and the second pump for infusing fresh blood. A problem with such roller pumps is the variation between pumps of the volume being pumped, variations as much as 6% have been noted. Such a variation would be clinically significant.